Taking a stab..........

How about a vapor lock? Fuel line getting hot between the cylinders. Clogged petcock strainer? Intermittent open, or short, to the main breaker? Maybe a loose connection. How about a bad wire to/from the igintion sensor? Brain damage? Stock electronics are questionsable at best, especially if the have been subjected to a sudden impact. Bad coil/loose wires? Loose wires on the ignition switch or a bad switch? Bad kill/run switch? Bad ground somwhere?

Just guessing.......

 

The ignition module may be on its way out {its a good upgrade if you don't have it} or the fuel tank is not venting, try cracking open the right gas cap.

 

Did you just start riding it again (after winter)? Our Sporty did that, I took the Carb apart for a good cleaning and no problems.

 

My EVO powered Heritage is developing a problem where it will suddenly die while at highway speeds, as if running out of gas, then will catch again. It dies abruptly with no backfire or anything like you hit the kill switch, then will take off again after a few seconds. This problem started on a 400 mile ride, the last 300 were in rain. I just thought it was the ignition getting wet, but it has now happened since then in dry conditions. I'm not sure how to diagnose such an intermittent problem. Anybody want to take a stab at this?

Check Battery wires and connections.....if the switch housing with the on - off switch got sooked it will SOMETIMES give a intermediate short in the switch its self.

 

Worn ignition switch will also do that.

 

Did you just start riding it again (after winter)? Our Sporty did that, I took the Carb apart for a good cleaning and no problems.

No, it was ridden before that. I managed to find a few warm days to get out through the winter.

Check Battery wires and connections.....if the switch housing with the on - off switch got sooked it will SOMETIMES give a intermediate short in the switch its self.

I wondered about that myself. I guess the kill switch is the first place to start.

Worn ignition switch will also do that.

Bike was VERY low mileage when I got it. Just up to 11600 or so now.

 

"Bike was VERY low mileage when I got it. Just up to 11600 or so now..."

The milage is meaningless. Brand new parts, sometimes, fail right out of the box, especialy electronics.

 

I just had a similar problem but it wasn't intermittent. It was under power in top gear. It turned out to be my float level.

 

I have a 1985 FLHT with an Evo and about 60K miles on it. It started doing what u describe about a year ago. I attacked the problem using the mechanic by braille techniques... in other words I replaced parts until it fixed the problem. I started with the cheap and easy parts, I replaced the battery, drained the tank, tried new fuel, changed the air filter and the plugs, then the coil and the wires. Then I changed the the VOES (vacuum operated electric switch) ALL to no avail. I then replaced the ignition computer. The original was not available so I put on a Screaming Eagle replacement (which required a little re-wiring) and this fixed the problem. I should have started with the computer. If u can find one that will plug in without re-wiring try it first and see if that does it. Good Luck.

 

I have a similar problem with my '95 heritage. Most of the time when it acts up, it simply won't idle. It will die like i hit the kill switch. It will start right back up, but will often die again as soon as i start to idle again. It will do this in fits of four to five times, then it runs perfectly again with no trouble for a month or two before acting up again. just recently though, it has started dying on me at cruise speed, just like it did at idle. It will again, start right back up, and after a couple of times doing it's dance on my last nerve, it will play nice again. I suspect it may be carb related though. I have a mikuni 42 mm flat slide. I have torn it apart and checked it over already, with no luck in finding the problem, but I'll just keep lookin'. It is so intermmitent, that it's almost impossible to trouble shoot. I could replace all kinds of crap, but I won't know if I hit the nail for a month or two. :dunno:

 

I have a similar problem with my '95 heritage. Most of the time when it acts up, it simply won't idle. It will die like i hit the kill switch. It will start right back up, but will often die again as soon as i start to idle again. It will do this in fits of four to five times, then it runs perfectly again with no trouble for a month or two before acting up again. just recently though, it has started dying on me at cruise speed, just like it did at idle. It will again, start right back up, and after a couple of times doing it's dance on my last nerve, it will play nice again. I suspect it may be carb related though. I have a mikuni 42 mm flat slide. I have torn it apart and checked it over already, with no luck in finding the problem, but I'll just keep lookin'. It is so intermmitent, that it's almost impossible to trouble shoot. I could replace all kinds of crap, but I won't know if I hit the nail for a month or two. :dunno:

Mine did it again last Friday, but instead of dying for a second, we nearly made it to a stop. When we were nearly stopped, I turned the ignition switch off, then on again, and it took off. It tried dying again almost immediately, and once again turning the switch off and on again worked. It hasn't acted up since, including a 330 mile ride Sunday afternoon. I have a new switch on order......I'll try to let you know if that takes care of it.

 

Ok, I know it's been a while now, have you had any luck with the problem? I ask because mine has gotten considerably worse in the last couple of weeks. I have already replaced the ignition module($300 frickin bucks) and the cam position sensor, the starter relay, and the circuit breaker. No luck yet. Soon I will replace the ignition switch, and possibly the start,kill switches. I have gone through most of the harness, looking for possible cuts/worn wires, and bad grounds.

Mine doesn't die at higher speeds, but mainly at idle. i have also pulled the carb apart, and checked the fuel line, and tank for problems, but no luck. I think it has to be something electrical, because I can't push start it when it does die at cruise speeds. I can pull in the clutch, and let it out at speed, but it won't restart, even after switching the ignition switch(the one on the dash) off and on again. Yet, once I hit the starter button, it will fire right back up. Sometimes it will die again immediatly, other times it will stay running. It seems to run fine, when it's not acting up, but it does not idle evenly when it is acting up. I just haven't found the smoking gun yet, so I wqondered if anyone else had.

 

GUILTY PARTY - Cam position sensor

But I only found that out AFTER I had replaced the ignition switch.
No problems since then, amounting to 3000 miles.
I guess that won't help you much, since you've replaced that already.

 

My 94 Heriatge has had the same problem. I'm 99% sure that mine was ignition switch. I had one wire that was just a little loose and I also took the switch apart and cleaned it and applied dielectric grease to all the terminals. Ran all day yesterday with no problems.

 

Yeah, today I pulled the coil off and cleaned the contacts on the coi, after I found some corrosion on the plug wires. Turnes out that the inside contact (where the plug wire makes contact) had quite a bit of carbon and corrosion in them. After I cleaned them with alcohol, I test rode it for awhile, with no problems.

 

Make sure to coat the coil terminals and the end of your plug wires with dielectirc grease. This will cut way down on the corrosion problem.

 

Petccock isn't suppling the carb fast enough and the carb is running out of gas.....worth a check.

 

My '88 Softail Custom developed this problem after I got it back this past spring from crash repairs at my local HD shop. Complicating the troubleshooting, at least for me, is that I had the cam/carb/aircleaner upgraded while the bike was in pieces. I first thought this was carb related, but after researching the problem it sounds like it is electrical.

Mine has only cut out once, and that was while cruising at 40 mph. It turned over but would not start initially, so I turned the ignition switch off and then on again and it fired right up.

Normally, about every 100 miles or so, the engine will stumble like it is going to shut down, and then it will backfire once or twice. After the backfire it will run fine again for many miles. After reading this thread it sounds like the ignition switch and then the kill switch are logical places to start. Am I on the right track here?

 

My local indie said the cam position sensors fail due to engine heat. Mine started out as just a brief cut out, as if I turned the kill switch off, then back on. The dead intervals got longer as time went, but were still only occasional until near the end. It usually didn't backfire when catching again.
YMMV.

 

i just pulled the petcock on Sunday, both to see if the screen, or tube was blocked, and because it seems to leak a very little bit. The leak is just enough to get gas stains on the oil tank, and primary. Neither is the problem, but as stated, it was worth a look. I haven't had it die on me since I cleaned the coil contacts for the plug wires(no dielectric grease yet, but I will). But I have developed a new problem not directly related, but a result of the original problem. Last Saturday I was in San Francisco to see my son( he was in the hospital). When we left Saturday morning, it died on me every time I came to a stop, which was every 25 feet or so in traffic. I must have restarted the bike at least 15 times within a half hour.:badmood: As a result, I chipped a couple of teeth off of my starter ring gear.:crying: So I ordered a replacement today, in the hopes that I can get it put back together before the weekend( I had it overnighted) If not, I may just go postal on the damn thing:beatdh:

 

O.K., over the last couple of weeks my problems have gotten much worse - now I can barely get the bike started. After 6 to 8 attempts to start it will backfire and then it always starts on the next attempt. I dropped it off at my local HD dealer tonight after work. Hopefully they will be able to diagnose and repair the problem. I will report back with results...

 

Picked up my bike from the dealer yesterday, and so far it runs great. Started right up, no backfiring, stumbling, or stalling. They replaced the ignition module with a Screamin' Eagle unit, and had to replace the wiring harness to work with the new module. They also replaced the sensor plate. I had them put in a pair of platinum SE spark plugs too.

 

Mine went throuhg another dying spell just after my last post. So I replaced the plug wires(fiasco with the dealer), and the ignition switch. Since then, it has run like a champ. I had the same connecter problem when I replaced my ignition module. I called every dealer in the area(6), and only one had a SC unit in stock. So after two hours of driving to get the unit home, I pulled it out of the box, to see that the plug is different than mine. I have a 95 Heritage, and appearently the switched plugs somewhere around that time. So I call the dealer back, and he tells me that after double checking, it's the right unit, and plug. long story short, I had to cut the connecter off, cut my old connecter, and solder the connecter to the new box. It workes fine, but now I have a spare $300 ignition box, with a newer style connecter. i haven't soldered it onto the box yet, just in case I need it, or sell it to someone with the old style connecter.

 

Same type of problem with 89 FLHTC

I'm having a similar problem with my 89 FLHTC. It started dying without warning while tooling along. I can pull over, and try to start it and it will crank over but won't start. If I turn off the ignition and let it sit a minute, it fires right up and will run fine for a while then do the same thing. I'm almost sure it is electrical due to the fact that it doesn't sputter or surge before dying, it just cuts out completely. The lights are all on so I think it is in the ignition somewhere. Any ideas will be appreciated.

Thanks
Beagleman

 

I'm having a similar problem with my 89 FLHTC. It started dying without warning while tooling along. I can pull over, and try to start it and it will crank over but won't start. If I turn off the ignition and let it sit a minute, it fires right up and will run fine for a while then do the same thing. I'm almost sure it is electrical due to the fact that it doesn't sputter or surge before dying, it just cuts out completely. The lights are all on so I think it is in the ignition somewhere. Any ideas will be appreciated.

If you have time pull a plug next time it dies and check for spark.
When my cam sensor went bad, there was no spark.
It usually didn't stay dead long enough, 'till close to the end.
Sounds just like my problem, except it would start running before coasting to a stop.